Abstract # 94:

Scheduled for Friday, June 18, 2010 07:00 PM-09:00 PM: Session 18 (Medallion Ballroom C/D/E/F) Poster Presentation


A. E. Parrish1,2, M. J. Beran2, B. Wilson3 and S. F. Brosnan1,2,4
1Department of Psychology, Georgia State University, Atlanta, GA 30302, USA, 2Language Research Center, Georgia State University, Atlanta, GA USA, 3Economic Science Institute, Chapman University, Orange, CA USA, 4Neuroscience Institute, Georgia State University, Atlanta, GA USA

We know little about how the strategies that humans use to make economic decisions evolved. Although humans and nonhuman primates share many of the same decision-making characteristics, including negative responses to inequity, loss aversion, and an endowment effect, direct comparisons using the same tasks are needed. Critically, these tasks must involve no verbal instruction, or the species begin on unequal footing. This study investigated how chimpanzees (Pan troglodytes) and capuchin monkeys (Cebus apella) respond to the Assurance game, a coordination game. Individuals were paired and payoffs were contingent upon their choices. If both individuals made a "cooperate" response, both received the maximum payoff, but if one made the "defect" response (for a lower payoff) then the other received nothing unless they, too, defected. Thus, the best strategy was to coordinate on cooperation. Eight of 10 chimpanzee pairs matched their partner’s moves [all X2s >6.63(1), all P's<0.01], but they did not preferentially choose cooperation. Only a single pair of four capuchins matched their partner [X2=7.92(1), P=0.005, all other P's>0.15]. In comparison, humans typically match, and approximately half of the pairs coordinate on cooperation. Thus humans were the most likely to cooperate, outperforming both nonhuman primates. Chimpanzees outperformed capuchins, typically matching their partners, but even the apes failed to consistently find the maximizing solution, coordinating on cooperation.